The International Electrotechnical Commission (IEC) and the Telecommunications Industry Association (TIA) create detailed rules for fiber optic components, manufacturing, and testing. These standards focus on things like connector geometry, ferrule cleaning, and insertion loss. d suppliers of electrical construction services. Existence. Recommendation ITU-T L. It details the FDB housing, FDB fibre management system, cable attachment and termination system, and specifies the mechanical and environmental characteristics.